Electric heater



May 26, 1925.

0. CONRADTY ELECTRIC HEATER Filed Feb; 17, 1325 CHROM/l/M F I. CHROM/UAM Patented May 26, 1925. V

UNITED STATES o'r'rma CONBADTY, or-

NUREMBEIBG, eamcm.

ELECTRIC HEATER Application filed February To all whom it may concern:

Be it known that I, OTTMAR CONRADTY, a citizen of the German Republic, residing at Nuremberg, Germany, have invented certain new' and useful Improvements in Electric Heaters, of which the following is a specification.

This invention has reference to improvements in electric heaters, and it relates in particular to means of increasing the life and resistibility of the connecting points of the heating rods or resistances, as compared with the means heretofore suggested.v In accordance with the previous art the connecting contacts for electric heating rods of silicon-carbide have been obtained by providing the connecting terminal portions of the heating resistances with wlndings of wire, the said terminal portions being then coated with copper, nickel, silver, or aluminium either by the metal sputtering process or by galvanic means. There is, however the drawback with all the coatings referred to, as heretofore practised, that the netals commonly employed possess a relatively low melting point or that they became oxidized at the temperatures employed, upon exposure to the air in the usual manner of utilization thereof, that is to say, in view of the high temperatures generated by such heating rods, so that the surfaces became non-conductive, thereby producing high transmitting resistances and injurious additional heating.

lVith a view of avoiding these difliculties it is one of the main objects of this invention to manufacture the well know-n metal coatings at the connecting ends of the heating rods from a difficultly melting metal of high resisting quality against oxidation, for which purpose chromium has been found to be particularly adapted. The coating of chromium at the ends of the heating rods may be applied either by galvanic or by any mechanical means. Among the important adi 'antages resulting from the previous coating of the connecting ends with chromium the combined properties of diificult fusibility with substantially the complete unability of oxidation, which heretofore could not be accomplished in any of the metal employed,

11, 1025. Serial No. 9,876.

are particularly noticeable. The melting point of chromium is about that of nickel. he absence of oxidation combined with the high melting point of such connecting ends results in an always constant transmittin resistance. Also. the so-called frying an the formation of fused beads'upon any temporarily occurring overloading of the connecting ends are avoided. The efiiciency of A the novel connecting means is further increased by also applying a coating of chromium to the metal fitting em loyed for the mounting of the heating ro s, such as terminals, clamps, screws and the like.

In the-accompanying drawings Fi re 1 is a view of an electric heating rod em odying the invention.

Fig. 2 is an end view of the heating rod, the same being shown mounted in a suitable fitting.

In the drawings A is the electric heating rod, B are the ends coated with metallic chromium and C are the metal fittings employed for mounting the heating rods, which fittings are also covered with a coating of chromium.

The invention has been described herein only in its broad aspects, and it should be understood that its manner of application is susceptible of modifications and changes, Without deviatingfrom the scope and spirit of the invention, as defined in the appended claims.

I claim 1. As new articles of manufacture, electric resistances with a coating of metallic chromium on the ends thereof.

2. As new articles of manufacture, electric connections for heating resistances, which consist of electric resistances having the ends coated with chromium-metal, metal fittings for said resistances in contact therewith, and a coating 'of metallic chromium on said fittings.

In testimony whereof I hereunto aflix my signature in the presence of two witnesses.

OTTMAR GONRADTY.

Witnesses:

ALEXEI v. PHILIProFr, P. J. RENELY. 

